1. Field of the Invention
This invention relates to a camera having a cartridge chamber into which a film cartridge is detachably insertable along its axial direction.
2. Related Background Art
FIG. 15 is a perspective view of a film cartridge 2 having the same construction as disclosed in U.S. Pat. No. 4,832,275. The cartridge 2 includes a cylindrical portion 2a in which a spool shaft 2e is rotatably mounted, and a film feed-out portion formed integrally with the cylindrical portion 2a in such a manner as to extend in a tangent direction to the cylindrical portion 2a. A film 1 is stored inside the cylindrical portion 2a as it is wound around the spool shaft 2e. An engaging portion 2c is formed at an upper portion of the spool shaft 2e in such a manner as to be engageable with a driving member (not shown) provided in a camera. The film 1 is fed out from the feed-out portion 2b when the spool shaft 2e is counterclockwise rotated by the driving member in a direction as indicated by an arrow of solid line of FIG. 15 and it is rewound when the spool shaft 2e is clockwise rotated by the driving member.
Since this type of cartridge 2 is so designed that the film 1 is fed out by rotating the spool shaft 2e as described above, when the cartridge 2 is loaded into a camera, it is not necessary to draw out the film from the cartridge 2 and then wind it around a take-up spool which has been required for a conventional 135-type cartridge, for example. Therefore, unlike a conventional camera, a camera usable for this type of the cartridge 2 is not required to be so constructed that the back surface of a camera body is designed to be wholly opened and this opened back surface is closed by a back lid. In this type of camera usable for the cartridge 2, a cartridge loading work is more facilitated if the camera is provided with a cartridge insertion inlet having a slightly larger aperture than the diameter of the cartridge at a bottom portion of the camera body and a cartridge lid movable so as to open and close the cartridge insertion inlet, and the camera is so designed that the cartridge 2 is insertable into a cartridge chamber along its axial direction while the cartridge lid is opened.
In a camera usable with cartridge 2, a detection device for detecting whether a cartridge has been loaded into the camera is required to electrically carry out an initial feed-out operation of a film, for example, interlockingly with a closing operation of the cartridge lid after the cartridge is loaded into a cartridge chamber of the camera. If the detection device is constructed by a detection switch whose switch-on operation is actuated by the load of the cartridge, and whose switch-off operation is actuated by the non-load of the cartridge, the film initial feed-out operation may be carried out when the close-state of the cartridge lid is detected after the detection switch is shifted from the switch-off state to the switch-on state.
However, the following problem occurs in such a camera if the camera is so constructed that the detection switch is disposed at an inner side of the cartridge chamber and apart from the film insertion inlet, and the detection switch is switched on when the cartridge is substantially completely loaded into the cartridge chamber while it is switched off when the cartridge is slightly drawn out in the above completely-loaded state.
In a case where a cartridge storing a film whose photographic frames have been wholly photographed (hereinafter referred to as "used film cartridge") is halfway or partially drawn out (unloaded) from the cartridge chamber and then reloaded into the cartridge chamber, the detection switch is once switched off at the time when the cartridge is slightly halfway drawn out from the cartridge chamber, and then switched on at the time when it is reloaded into the cartridge chamber. Therefore, when the cartridge lid is closed after the cartridge is reloaded into the cartridge chamber, there occurs an unfavorable circumstance that the initial feed-out operation of the film from the reloaded cartridge is unfavorably started again. Such a circumstance frequently occurs when a user draws out a used film cartridge halfway or partially from the cartridge chamber, but re-loads the film cartridge into the cartridge chamber because the camera will not be used afterwards and the cartridge is better kept in the camera.